Obama encouraged a crowd estimated at 30,000 on Bascom Hill to take advantage of in-person early voting that starts Oct. 22 and runs through Nov. 2. University police provided the crowd estimate.

The crowd waited for hours Thursday in periodic rain showers and dropping temperatures to cheer Obama during his 22-minute speech that touched on key campaign themes of funding education, creating jobs and pushing for tax fairness.

Many were anxious to hear what the president would have to say after what some have called a lackluster performance in the first presidential debate Wednesday night. But instead of addressing his own performance, Obama went after his opponent.

"I just flew in from Denver, and I was telling folks, when I got on the stage, I met this very spirited fellow who claimed to be Mitt Romney," Obama said at the Madison rally. "But I know it couldn't have been Mitt Romney, because the real Mitt Romney has been running around the country for the last year promising $5 trillion in tax cuts that favor the wealthy, and yet the fellow on the stage who looked like Mitt Romney said he did not know anything about that."

The president continued with his campaign stump speech emphasizing his slogan of moving forward. But Obama also took another debate-related swing at Romney connected to plans discussed Wednesday night to cut funding for public broadcasting to shrink the deficit.

"But I just want to make sure I got this straight," Obama said. "(Romney) will get rid of regulations on Wall Street, but he's going to crack down on 'Sesame Street.' Thank goodness somebody is finally cracking down on Big Bird. Who knew he was responsible for all of these deficits?"

The Obama campaign on Thursday also responded to criticism of Obama's debate performance.

In comments to the White House press pool, advisor David Plouffe said they knew Romney would do well in that format and felt some were "itching to write the Romney comeback story." But Obama's aides conceded Thursday that the incumbent must get sharper in countering his opponent and crisper in explaining his ideas to the American people.

The crowd on campus started lining up early, well before the gates opened around noon. The line wrapped around Bascom Hall west along Observatory Drive, where thousands stood in line hours before the gates opened to see the president.

"I'm worried I won't get on Bascom. When I got here at 9 (a.m.), there were probably a few thousand already. My biggest concern is being able to see and hear the president speak," said Elissa Hersh, a UW-Madison student waiting in line.

"So I'm happy it made the day worth it. All we missed at school today was social studies, and they said this would make up for it," said Heidi Kumm, who brought her daughters to see the president.

But just before 2 p.m., security stopped admitting people to the event, saying the crowd entering Bascom Hill had reached capacity. That left scores of supporters without a view of the president in Madison.

"We parked and took a city bus here and walked. And we waited in line, and now, nothing. (My daughter) is not going to get to see the president. It's like a once-in-a-lifetime thing. It's very disappointing," said Stacy Hillary-Nolan, who was turned away with her daughter after Bascom Hill reached capacity.

UW-Madison police said that about 6,000 people were turned away after the event reached capacity.

Many classes and exams were canceled at the university Thursday because of the presidential visit. UW-Madison police said no arrests were made, and no other significant law enforcement issues were reported in conjunction with the event.

Three UW-Madison professors said students shouldn't have to register with the Obama presidential campaign to attend the rally.

Students were required to supply their phone number and email address to the Obama campaign and click "I'm In" in order to get a free ticket to the president's appearance at Bascom Hill.

Political science professors Donald Downs and Ken Mayer and law professor Ann Althouse sent a letter expressing their concerns to university administrators Wednesday.

Vice Chancellor Vince Sweeney said the university was simply trying to provide as much information as possible about the rally by putting the Obama campaign link on the university's website. Sweeney said the school doesn't manage the Obama link and doesn't collect the information from it.

Republican Gov. Scott Walker released a statement Thursday on Obama's visit to Madison, saying that Obama "chose to recover from a bad debate in one of the most liberal places in America. Last night, swing voters in Wisconsin clearly saw that Mitt Romney is the better choice to get America working again."

Copyright 2012 by Channel 3000. The Associated Press contributed to this report. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.